Intravenous salbutamol and aminophylline in asthma: a search for synergy.

Abstract
The bronchodilation produced by increasing i.v. doses of aminophylline, salbutamol and a combination of aminophylline and salbutamol given in random order was determined in 10 stable asthmatics on 3 consecutive days. On a 4th day response to placebo injections was determined. Forced expiratory volume in 1 s (FEV1) was measured at 2 min intervals after each dose until FEV1 returned to a new baseline. At no dosage level was there synergy between the 2 agents in terms of mean percentage increase in FEV1 or the integrated response. The failure to demonstrate synergy has implications with respect to the clinical use and the underlying mechanism of action of these drugs.